Naturalistic use of psychedelics does not modulate processing of self-related stimuli (but it might modulate attentional mechanisms): an event-related potentials study comparing non-users and experienced users of classic psychedelics

Regular, naturalistic use of classic psychedelics (15 or more lifetime experiences) does not appear to alter the brain's basic representation of self, as measured by the P300 event-related potential response to one's own name. In a cross-sectional study comparing 56 experienced psychedelics users with 57 non-users, no difference was found in P300 amplitude evoked by the participant's own name. However, psychedelics users showed a smaller increase in P300 amplitude when processing a task-relevant target name compared to non-users, suggesting that repeated psychedelic use might affect how attentional resources are allocated to task-relevant stimuli rather than changing the long-term neural representation of self.

Study at a glance

Abstract

Classic psychedelics are able to profoundly alter the state of consciousness and lead to acute experiences of ego dissolution – the blurring of the distinction between representations of self and the external world. However, whether repeated use of psychedelics is associated with more prolonged and permanent modifications to the concept of self remains to be investigated. Therefore, we conducted a preregistered, cross-sectional study in which experienced psychedelics users (15 or more lifetime experiences with psychedelics; N = 56) were compared to non-users (N = 57) in terms of neural reactivity to a Self-name (i.e., each participant’s own name) stimulus, which is known to robustly activate a representation of self. Two control stimuli were additionally used: an Other-name stimulus, as a passive control condition in which no reaction was required; and a Target-name stimulus, to which participants provided a manual response and which thus constituted an active control condition. Analysis of the amplitude of the P300 ERP component evoked by the Self-name revealed no difference between the psychedelics users and non-users. However, in comparison to non-users, psychedelics users exhibited a smaller increase in P300 amplitude when processing the task-relevant Target-name (in relation to both Self- and Other-names). Therefore, our data suggests that regular naturalistic use of psychedelics may not be related to long-term changes in the representation of self, but it might potentially affect allocation of attentional resources to task-relevant stimuli.